Tests: why do they purge the DNS cache?

[alibosworth]

Thanks for this tool! I just opened a PR that you might find useful.

I was a bit surprised that the tests purged my DNS cache and this feels a bit invasive. Typically a project's tests are self-contained and don't make active changes to the system they are run on. If it is necessary to do that, I suggest a warning at the start "this will purge your DNS cache because... press enter to continue" etc, and then a flag/env var so it can run on CI without that interactive component.

Also I encounter an error (red x) but it reports as all passing:

I'm opening this as a discussion instead of an issue because I'm not sure it IS an issue, but I was definitely surprised by it.